Diatoms, key members of marine and freshwater ecosystems, have genes for the urea cycle, for using lipids as an energy source, and for synthesizing their ornate, silica-based cell walls. Abstract »| Full Text »| PDF »| Supporting Online Material »|

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Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for 20% of global carbon fixation. We report the 34 million–base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand–base pair plastid and 44 thousand–base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for 20% of global carbon fixation. We report the 34 million–base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand–base pair plastid and 44 thousand–base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.

Revision as of 21:57, 24 March 2008

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Diatoms

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for 20% of global carbon fixation. We report the 34 million–base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand–base pair plastid and 44 thousand–base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.

Fuels for space

Notes from speaking to David Thompson

Oxygen - O2 as byproduct of photosynthesis

Hydrogen - via the biohydrogen route

nitrogenase, the enzyme that fixes N2 to NH3(amonia)ozene

, as a normal part of its function it produces H2 albeit at a much slower rate than NH3, its a side reaction. but if you force the reaction in an atmosphere with zero nitrogen, then you get H2 production exclusively.
(Hydrogen-2, H-2, 2H (a.k.a. Deuterium), an isotope of Hydrogen (1 proton, 1 neutron, 1 electron))

Hydrizine

Deep sea bacteria that make hydrazine as a free metabolic intermediate. (Hydrazine is used as a bipropellant in combination with O2 I (DT) believe,and some of its derivatives are used in combination with other liquid rocket fuels...)

Guanidine

A strongly alkaline crystalline compound, NHC(NH2)2, formed by the oxidation of guanine and found in the urine as a normal product of protein metabolism. It is commonly used in the organic synthesis of plastics, resins, and explosives. (answers.com)
Guanine production was hypothetical, it would involve tweaking the purine biosynthetic pathway, and i think i mentioned a purine efflux pump... http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=181001